Boulders and Rincons are very much entry level mountain bikes. They will get you out there and riding. If you are the type to push limits and ride a lot, you may find yourself looking for more after a bit. But that is what an entry level bike is supposed to do. It gets you out there to see if this whole scene is something you'd like to do often. If it is, then ride your entry level bike, replacing only what breaks with modest replacement parts, saving your sheckels for something nicer down the road when you figure out exactly the type of bike you really want.
If you and the wife/gf are just looking for some occasional exercise, they will get the job done reliably.and economically.
If you are riding real MTB trails, a real MTB is the way to go. But if you're actually just 'path' or dirt road riding, a hybrid will also do that just fine and you (and/or your wife/gf) might prefer the slightly more upright riding position of a hybrid vs. the more agressive and leaned forward riding position of a mountain bike.